Method for producing electrical oscillations of high frequency from direct current.



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.ME'HM FOR'PRDJCHNG ELECTBIGAL OSCIL'LATIONS 0F HIGH FREQUENCY FROM DiRECT CURRENT.

PFLICATION FILED APR. 7. |914.

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Specication Application filed April 7,

To il wlmi/1, z5 may concern."

lie it known that l. liloinnrr voN Lnrnn, a suhjcct oic the ling et Prussia, residing at eriiii-YVilniersdor. in the Empire of Germany. have invented new and useful linprorenients in ilethodsy for Producing Electrical (lucillal'ions ot High Frequency from Direct (lui-rent hr Changing' the Charge of a Condenser. oi which the 'following is a. speci licati on.

ri`he application of connniitators` for producing electrical oscillation has heen l-:norfn tor a number of lYears. i

ln the accompanying drawings have illustrated in a diagralnlnatical manner different- Systems 'for producingY electrical oseillations et high Jfrequency ifroin direct current, which are Specifically referred to in the description hereinafter.

Figures l and 2 illustrate arrangements .euch as are usuall)7 employed with known methods.

Figs. 3 and #l are curves illrieti-util@l the theory underlyingmy prefsent invention.

liig. 5 illustrates a` system embodying;7 my present invention for producing electrical oscillationa of high frequency.

Fig. (l is a modification of the H if'stein shown in Vig. 7 shows a Special construction ot coni nulla-.tor ciii'ploved in accordance with iny present invention and haring` stationary electrodes and rotating Hhort' ciicuitinjg nicn'ihers.

hier. F4 shows a System in which the coniinutation iS performed hy means` of artilirlal ignition; and

Fig". il illustrates: ay combination of rotai ing' electrodes with a stationary blocking condeneer.

ln most cases as shown in the first two figures a reservoir condenser Vl isi arranged which fed from the souri' oi dircfft'current 2 and rliythniically d ha'rgled in an oscillateur circuit. Viin this. War the diS- charge takes place either in accordance with Fig. 1 hy a periodical change ot charge. or in accordance with Figi. 2 h v periodiealli7 cl'iarging` and discharging a. blockingY condenser 3. The conunutator 'is formed hf; a revolving Spark gap The couplingr coil 5 transmite the oscillating: energyv oi' high frequency to the circuit of antenna.. .into the Supply circuit choking eoileI 7 are inserted in a usual manner for the pin-pogo of pro- FREQUENCY Fll'lt www ,etters Patent. r'gi (i j; p17),

f. CTalu 336,288.

tecting the source or current iroin returning high frequeninT energy.

These, arrangl'ciiicnt 4 can only work .steadilyY if the capacit)7 of rcserroir condenser Il rerifv large in ci'nnparieon te the capacity of the lilocl'zingi condenser il. Theoretieally. a state of perfect steadiness obtained only if the proportion ot' the capacities is infinitely large. 'l'or the lplloming reason. the r'el't induction oil the supplyV means which self induction is further increased h r the iin pedance or the protectingv choking coils 7 the needing of the condenser l follows an oScillater)Y course. Thus. for infatance. on chargingr the initiall)Y perfectly discharoeil con deneer l' the potential olf the condenser c will in accordance ith diagram B. oseillate far ahore the Yalue of the feeding potential i@ until the point 1S iS reached: then the oscillation graduali;Y decrease#A to the value ll. l'f on the sul'licien npproach oi" the electrodes the cha or charge iS ellccted al; ahout the inonient f, thc polen' ial or' the conf denser al' the moment the spark jumps eduals ck as nia).` he interred from the diag'rani. To cach other nion'ient f. f3 f l correspondsanother potential c. if.; c... n further pursuing the electrical phenomenon it appears that hy methode ot this kind not only dissunii'iorni clincharginel vpotentials would result hut also tl-y rhythni of discharge would heroine dieuni'lu'nil and eren. `would sto; sometimes., or partial diSchar-gea would occur. @n the other hand it the condenser l conipffirativel),7 large in compari` non io the blocking condenser only.'y a mail portion ol the charges is cinieuu'i'ud with each spari( with the result rha'i; the liuctuation olE 'the ilioential deereaeu rlhe operation he cornes the more regular the larger condenser .l is in coinpaiieon with the blocking condenser Apparenti'ifv this has also heen found lo.' experiments in eases where a clear conception oi" the. phenomenon was missing 'ifor the reipiircnient to inereaie as 'liar as poe- .eihle the condenser l in comparison to the blocking cond-enger 3 ina?,v he found in almost all pape/rbl dealing;- with 'this and similar methods.

a matter oi' cours 'ille use of condene` erI which ought to l are a capacity ot' a far higher order than thev blocking' condenser ie economically and pract-i@albv so cliicult as to exclude the application of these meth-- ods from actual practice. it is true that a lll@ , 46 by timing the uniform operation may be obtained by starting the periodical spark discharges not until 'the supply oscillations have fully decreased,

vith Ithe result that at the moment of the commutation the condenser' receives the supply .potential E. Since with the oscillatory charge of a condenser always exactly half of the energy supplied is lost this system yields an uneconomical ei'fect.

By means of the novel method hereinafter described a perfectly lsteady operation and a .good efficiency is obtained notwithstanding the fact that a condenser is employed of a capacity not larger, or not essentially larger, than the capacity of the blocking condenser.

The method consists in choosing both condensers of ay .capacity of an equal order and tuning the supply circuit in such a way to gd the rhythm of thesparksthat the .high trequency energy,obtained on eqiialrzing the potential of both condensers and incidentally the energy derived from the source of current will ,be proportional to the square of twice the supply potential. 4 l

'This is 'made possible if the condcnsers connected in series at the moment of the spark are given a total potential that is twice as large as the supply potential; for

lg'only in this case the effect will. correspond 'tothe square of twice the supply potential. i Vith the old method according to Fig. 1 this demand is complied with; however, only by using a condenser 1 of theoretically Bvinfin'ite size. ln this way the blocking condenser is charged to the full potential of condenser 1, that is, to the full supply potential, and offers this potential for the next spark in an inverted position with the result that an initial spark potential of twice the Value of the supply potential is produced.

According to the new method the requirement as explained above is complied with by using condensers of equal or similar capacity supply circuit iufcordingly. From the diagram shown in Fig. il it will be observed that the first oscillation emitted produces an initial spark potential ol almost twice the value of the supply potential it' the spark is produced at the moment to corresponding to the extreme value of the oscillating potential, or it the lengths oi the Waves oi the oscillations in the sul'iply eircuit are chosen in a way that the latter will reach their extreme value just at the moment the spark is produced. The wave length l., corresponding to this condition will be called hereafter critical wave length. 'After the oscillation has come to rest the potential of condenser 1 will not again come Vto zero but assumes the value of the equalized potent ial V changing diagram q 3 to diagram 4 during the operation. The j initial'spark potential ciuals in this case $5 also the total of the maximum potential prevailing in condenser 1 at the moment of the spark, and also the potential V offered by the inverted blocking condenser. If the capacity of both condensers is perfectly equal for both potentials the value 1 E and '1% E will be obtained by way of calculation so that their total potential again equals twice the supply potential.

For the purpose ot' applying the idea of this invention adjustable self induction or choking coils 7 (Fig. of sutlicient size are inserted into the supply-circuit, and with a given speed ot' the conunutating device the self-induction is increased to such a degree that the critical wave length )m or a larger wave` length lift-Al results. The supply circuit must always be tuned in accordancewith the speed ot' the commutating device. This tuning eli'ect may be easily obtained by the insertion of a sufliciently large selt'induction` lor it is not necessary, as already mentioned, to relyr upon an accurate tuning of the critical wave length 1 but a larger wave length may also be chosen.

In this latter case also uniformity is obtained but not so with a smaller wave length; because with all smaller wave lengths the maximum of oscillation 18 is already formed prior to the occurring of the spark, whereby the further course of oscillation is determined. wave" lengths, however, the oscillation is brought to a stop before the maximum is reached, that is in that part ot the curve that is ascending toward point 18.. vThereby the curve for the next charge is enabled to adjust itself to the rhythm ot the discharges.

Marconi has proposed and applied a tuning of the supply circuit, but under different conditions and for a diti'erent purpose.. For a description of Marconis systen'i, reference may be had to U. S. Patent 951,64() and British Patents 20,119 ot' 1907 and 18,524. of 1909. A dcscril'ition will also be found in Zennecks book entitled Lehr/melf. der 1Km/Hosen Telef/rapita, 1913, 11S, pages 241 to 217. lVith Marconis arrangement the coi'nlenser provided in the oscillatory circuit is temporarily discharged by means of a Jfast rotating short circuiting wheel, by which at the same time the source ot eurrent is also short circuiled. a quickly increasing current starting with each discharge. To prevent a` too violent action ot the short circuit Marconi tunes the supply circuit .so that thc supply current oscillates through the zero value at the moment the short circuit occurs, and in addition hc makes the short circuiting wheel rotate with such extraordinary speed that the arcs of the short circuit that are forming will he ruptured in time. lt the short circuiting wheel would go slower violent short circuits would occur in spite of the tuning. Hence, the timing 'ith all larger rhythm ot' the nections are made and broken by artiicial ignition or prevention of the sparks, such devices consisting essentially of a number or stationary electrodes, pairs of which are bridged alternately' by auxiliary sparks, whereby the current is caused to change its way each time. Such spark gaps have already been used in place of normal switches.

It is therefore irrelevant for the purpose of the present invention whether the dielectrical strength of the air space between the electrodes is diminished by approaching the latter or whether this diminishing is obtained by artificial ignition, namely by ionization. It is only essential that the potential of the oscillatory circuit at the moment of the discharge, that may be started by either of the described methods, possesses approximately the double' value of the potential of the supplying dynamo or mains.

The diagram of Fig. 8 may be used in connection with the artificial ignition. The electrodes l0, l0, 1l, 11, are artificially ionized alternately.

It 's evident that in this Way the blocking condl ser is periodically commutated, each commutation producing a train of electrical oscillations.

By 4means of the adjustable self induction coil 7 the supply circuit is tuned, in 'the manner described above, to the rhythm ot the sparks, z'. e. yto the rhythm of the artificial ionization.

Shoiild any disturbing influences of the gradually decreasing wave trains upon the new starting ones occur it will be orp advantage to choose the frequency of the supply circuit in. such a way that it corresponds not only to the rhythm ot the sparks but at the same time to an even fraction of the number of the high frequency oscillations.

The rotary commutating dericc can be rendered fit for combination with artificial ignition il" the discharge circuit is so arranged that even thc maximun'i potential difference which is attained -in the moment of the completion of the mechanical commutation does not suffice to cause the discharge. Then, it is possible. by means of additional auxiliary potentials, or ionizations, produced in the commutator, to start the oscillatory discharge with great precision at `any desired position of the commulatoigfor instance when both electrodes actually present each other their full surfaces.

lVhat I claim is: y

1. ln a system of the class described comprising a. source of current with tuning means connected to an oscillation circuit containing' a spark gap, reservoir condenser and blocking condenser, the condensers having capacities-of an equal order, the herein described method of ,producing electrical oscillations of high frequency which consists in charging the reservoir condenser, qzlosing naar the circuit through the spark gap and blocking condenser to produce a train of sparks, and so timing the feedingl current Wit" o spect to the rhythm ot' the train oi sparks that, at'thc moment of ignition, the condensers Will produce a resulting spark potential. which is substantially equal to double the value of the feeding potential. V

2. in aV system comprising a source ot' di rect current with tuning means comiectcd to an oscillation circuit containing a spark gap7 a reservoir condenser and blocking con-- denser, the condensers haring capacities o? an equal order, the. herein described me had of producing electrical oscillations of high frequei1cy\wl1ich consists in chznging the reservoir condenser, closing the oscillation circuitv periodically7 through the spark gap and blocking condenser to produce a tra Yu of Sparks, and so tuning tlu` 'Feeding ci rent vith respect to the rhythm ot' the train oi sparks that,- at the moment of ignition, the condensers will produce a resulting spark potential equal to double the value of the feeding potential. 4

3. In a system con'iprising a source of direct current with tuning means connected to an oscillation circuit containing one or more spark gaps having a constant gap leap i, one or more spark cally variable gap length, a reservoir coudenser charged by. said source ot current, and a blocking condenser, said condensers haring capacities oi' an equal order, the

herein described method of producing elec trical oscillations of high frequency which consists in charging the reservoir condenser, closing the oscillation circuit pcrifjidically through the spark gaps and blocking condenser to produce a train of sparks, and so tuning the feeding current with respect to the rhythm oi the train of sparks that, at the moment oi ignition, the condensers will produce a resultingr spark potential equal to double the value of the feeding potential.

4. ln a system for producing high frequency electrical oscillations, 'the combination ot' a source ot' direct current, an oscillation circuit including a reservoir condenser charged by said source ot' gap, a blocking condenser, and means for closing the oscillation circuit to produce a train of sparks, said condensers haring capacities of the same order, and moans -tor tuning 'the direct current supply with respect to the rhythm of the train of sparks to produce a resulting spark potential which is equal to double the value of the feeding po tential.

5. In a system for. producing high frequency electrical oscillations, the combination of a source of current, reservoir condenser charged by said. source of current, a blocking condenser, said condensers having capacities of an equal order, means for clos-- gaps haring a peiio-dic current, a spark j s o, fi,"

lli@

negoce 5 ing a, circuit 'through seid condensers to dis, charge the reservoir condenser and produce n tr-iin of oscillations, and means for tuning the feeding current with respect to the rhythn'i oil' the train offoscilletions.

(i. ln :i system for producing. high lireN quencjy electrical oscillations, the combine- Atien eff e source of direct current, an oscilla.- tion circuit including n reservoir condenser charged by said source of current, one or more spark gaps having :i periodically vari- :dole gap length, one or more spark gaps havv ing a constant gap length, blocking condenser, and means for closing the oscilla- 4 tion circuit to produce e train of sparks, said condenser-s having capacities of an equal order,and means for tuning the direct eurrent supply with respect 'to the rhythm of the train of sparks to produce e resulting spark potential which is equal to double the value of the feeding' potentiel.

7. lin e system for producing high frequency electrical oscillations, the combine- 'tion oiF e source of direct current, e reservoir condenser charged by said source ol current,

n, spark gap, s blocking condenser, seid condensers having capacities ol an equal order, ineens for closing e circuit through send conx densers to discharge the reservoir condenser and Aproduce train of sparks, means for tunin the heating current with respect to Vtlfie'riytlnn of the train of sparks, vand a, third condenser of a, higher order than the reservoir and blocking condensers in p21-rallel with the source of direct current.

,8. In :i system for producing high frequency electrical oscillations, the combination of a. source of direct current, en oscilla tion circuit including a reservoir :condenser charged -loy seid source of current, spark gaps having e periodicallyl varie-ble mp length,'cther spark' gaps having aconstmt gcp length, e blocking condenser bein/veeny said other spark gaps, and ineens for closing the oscillation circuit to produce ,a train of sparks, seidv condensers having capacities of the same order, and means or tuning the direct current supply with respect to the rhythm or Athe train of sparks to produce a. resultinn spark potential which isequal to double tlie'value of therfeedingpotentiel. i"

EGBERT von Witnesses: i @LL WoLDnMAR HAUPT, HENRY l'rlAsrnn. 

